Sole assembly for article of footwear

ABSTRACT

A sole assembly generally including a flex plate, a heel spring and a heel cup. The flex plate may extend from the rear of the sole through the arch into the forefoot. The heel spring may be an elliptical spring and may have internal resilient stoppers that prevent the spring from bottoming out. The height of the stoppers may increase toward the rear of the sole. The stoppers may be extensions of the outsole fitted up through apertures in the elliptical spring. The heel spring may be disposed beneath the flex plate in the heel region. The heel cup may be disposed above the flex plate in the heel region. The heel cup may have an extension that extends upwardly a sufficient distance to cradle the wearer&#39;s heel to provide an enhanced forefoot lever. The flex plate, heel spring and heel cup may be a single unitary component.

BACKGROUND OF THE INVENTION

The present invention relates to footwear and more particularly to asole assembly for an article of footwear.

The technical performance of shoes, boots, sandals and other articles offootwear is dependent in large part on the sole assembly. The soleassembly not only provides a protective barrier between the wearer'sfoot and the ground, but can also play an important role in the way thatenergy is utilized by the wearer. The construction of a sole assembly iscomplicated by the fact that the human gait cycle transitions throughfour different phases. Although gaits vary to some degree betweendifferent people and different activities, a typical human gait includesthe following phases: (1) heel impact (or heel strike), (2) heel to toetransition, (3) forefoot compression and (4) toe off. The soles in manyshoes suffer in that they are configured to focus only on absorbingforce during heel strike and providing cushioning to the forefootregion.

A variety of conventional sole assemblies are reported to collect energyand return that energy during different phases of the gait cycle. Forexample, some existing sole technologies include a longitudinallyextending flexible plate that is incorporated into the sole. Generallyspeaking, the plate bends to store energy during the forefootcompression phase of the gait cycle, and then straightens during the toeoff phase of the gait cycle to return the stored energy. As anotherexample, a variety of sole technologies are available with a flexibleand resilient spring in the heel region. Unlike foams, which compress,these springs are configured to bend under a load and to return to theiroriginal shape as the load lessens. The size, shape and configurationsof these types of springs vary. Generally speaking, these types ofsprings are intended to store energy during heel impact and to returnthat energy during the heel to toe transition and forefoot compressionphases of the gait.

Although there are a variety of existing sole technologies that utilizea flexible plate or a heel spring, the performance characteristics of asole assembly can vary dramatically depending upon the specific way inwhich these technologies are implemented in a sole. If not implementedproperly these technologies can prove to be a detriment rather than anaid.

SUMMARY OF THE INVENTION

The present invention provides a sole assembly that includes acombination of components that are configured to provide assistancethrough all four phases of the gait cycle. In one embodiment, the soleassembly generally includes a heel spring and a flex plate. The heelspring may be disposed beneath the heel region of the sole. The flexplate may extend from the rear of the sole forwardly through the archregion into the forefoot region. For example, the flex plate may extendto a point roughly below the metatarsal heads of the wearers foot. Inone embodiment, the heel spring and flex plate are part of a single solecomponent. For example, the sole component may be molded from TPU orother relatively hard plastic materials.

In one embodiment, the sole component may also include a heel cup thatis shaped to closely receive a heel. The heel cup may be integral withthe heel spring and flex plate. In one embodiment, the heel cup is anextension of the flex plate and it includes a heel extension thatextends upwardly along a gradual curve to embrace the wearer's heel andprovide an enhanced forefoot lever. The heel cup may have upper flangesthat extend forwardly in an arcuate path selected to closely follow theexpected shape of the wearer's heel. In one embodiment, the heelextension follows a gradual curve that is undercut in the sense that itcurves back in a forward direction above a portion of the wearer's heelto help resist separation of the wearer's foot from the sole component.

In one embodiment, the heel spring is an elliptical spring having upperand lower arched segments joined at opposite ends. A portion of theupper arched segment may be generally coextensive with the flex plate.In one embodiment, the elliptical spring may be cantilevered in arearward direction beyond the flex plate and heel cup. In oneembodiment, the upper arched segment and/or the lower arched segment maybe shaped to provide controlled rigidity in different directions. Forexample, in one embodiment, the lower arched segment may in lateralcross section be shaped to define a central rail that extends in thelongitudinal direction to provide the lower arched segment with enhancedlongitudinal stiffness.

In one embodiment, the elliptical spring may include one or moreresilient stoppers disposed within the internal void of the spring. Thestopper(s) may extend into the internal void from the upper archedsegment or the lower arched segment. In use, the resilient stopper(s)prevent the upper arched segment from bottoming out against the lowerarched segment. The resiliency of the stopper(s) may be selected toprovide the desired resistance to further compression. In thoseembodiments that include stoppers, the elliptical spring may include aplurality of resilient stoppers spaced apart from front to rear in alongitudinal direction. The height of the stoppers may be selected forfunctional reasons. For example, taller stoppers will allow the springto collapse less before engagement with the stoppers. The relativeheight of the stoppers may also vary for functional purposes. Forexample, in one embodiment, the height of the stoppers may increasetoward the rear of the sole. In one embodiment, the elliptical springmay include two rows of stoppers. For example, the elliptical spring mayinclude a first row of stoppers along the lateral side of the sole and asecond row along the medial side of the sole. In one embodiment, eachrow of stoppers includes three stoppers spaced-apart along an arcuatepath.

In one embodiment, the sole assembly includes a heel outsole disposedunder the resilient spring, and the resilient stopper(s) are extensionsof the heel outsole that are fitted up through corresponding aperturesin the elliptical spring. Although the stoppers may be an integral partof the outsole, they may alternatively be separately manufactured.

In one embodiment, the sole assembly includes a forefoot outsoledisposed under the forward end of the flex plate. For example, anarticle of footwear incorporating the present invention may include aforefoot region into which the forward end of flex plate extends. Theforefoot outsole may cover the undersurface of the forefoot region,including a significant portion of the forward end of the flex plate. Inone embodiment, the central or arch region of the sole component may beuncovered by the outsole, thereby making it readily visible.

The sole assembly of the present invention may be incorporated intoessentially any footwear construction and may be combined with othersole components, such as a midsole, insole or footbed. In oneembodiment, the sole component and associated outsole parts are cementedor otherwise secured to the undersurface of upper having a closedbottom. A footbed may be fitted into the upper.

The present invention provides a sole assembly that is capable ofproviding high performance throughout all four stages of a typical gaitcycle. During the heel strike phase, the elliptical spring compressesand undergoes deformation, which among other things cushions the impactand stores some of the impact energy. If deformation of the spring isgreat enough, the spring engages the resilient stoppers, which provideincreasing resistance to further deformation. During the heel-to-toetransition phase, the elliptical spring “bounces” back propelling thefoot forward. If compressed, the resilient stoppers may also returnenergy during the heel-to-toe transition phase. During the forefootcompression phase, the flex plate bends along its length (particularlyin the forward section) to store energy as the foot flexes. During thetoe-off phase, the bent flex plate returns to its original non-deformedshape, thereby returning the stored energy. Depending on the momentumand angle of toe-off, this energy may help to propel the wearer forwardwhen running or upward when jumping. In use, the present invention mayprovide enhancements to both speed and jumping. The heightened heelsection of the flex plate provides a substantial lever to aid incompression (e.g. bending) of the flex plate during the forefootcompression phase. The resilient stoppers provide enhanced performancein part because they do not impede initial compression of the ellipticalspring, but only become relevant after the elliptical spring hascompressed an amount that can be predetermined. The present inventioncan be readily tuned for a variety of different application by adjustingthe characteristics of the various sole assembly parts. For example, therigidity and resiliency of the material forming the elliptical spring,the flex plate and the stoppers can be adjusted to provide differentsole characteristics. The real and relative heights of the stoppers canbe adjusted to also impact the performance characteristics of the soleassembly.

These and other objects, advantages, and features of the invention willbe more fully understood and appreciated by reference to the descriptionof the current embodiment and the drawings.

Before the embodiments of the invention are explained in detail, it isto be understood that the invention is not limited to the details ofoperation or to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention may be implemented in various other embodimentsand of being practiced or being carried out in alternative ways notexpressly disclosed herein. Also, it is to be understood that thephraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the invention to any specific order or number of components.Nor should the use of enumeration be construed as excluding from thescope of the invention any additional steps or components that might becombined with or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a shoe incorporating a sole assembly inaccordance with an embodiment of the present invention.

FIG. 2 is an exploded view of the shoe of FIG. 1 showing the soleassembly separate from the upper assembly.

FIG. 3 is a side view of the sole assembly.

FIG. 4 is a bottom plan view of the sole assembly.

FIG. 5 is a side view of an alternative sole assembly.

FIG. 6 is a sectional view taken along line A-A of FIGS. 3 and 4.

FIG. 7 is a sectional view taken along line B-B of FIGS. 3 and 4.

FIG. 8 is a sectional view taken along line C-C of FIGS. 3 and 4.

FIG. 9 is a sectional view taken along line D-D of FIGS. 3 and 4.

FIG. 10 is a sectional view taken along line E-E of FIG. 4.

DESCRIPTION OF THE CURRENT EMBODIMENT

An article of footwear in accordance with an embodiment of the presentinvention is shown in FIGS. 1 and 2 and generally designated 10. Thearticle of footwear 10 generally includes an upper assembly 12 and asole assembly 14. In this embodiment, the upper assembly 12 is agenerally conventional upper assembly utilizing a strobel constructionin which a foot-receiving upper 15 is closed on the bottom by an insoleboard 16 or other similar component (See FIG. 2). In the illustratedembodiment, the sole assembly 14 generally includes a footbed 18, a solecomponent 20 and an outsole 22. The footbed 18 is fitted into the upperassembly 12 atop the insole board 16 to provide support and cushioningfrom inside the upper assembly 12. In this embodiment, the solecomponent 20 is of a single unitary construction and it generallyincludes a flex plate 24, a heel spring 26 and a heel cup 28. The heelspring 26 may be an elliptical spring that is disposed in the heel ofthe shoe 10 generally below the heel of the wearer's foot. Theelliptical spring 26 of this embodiment defines a central void 36 andincludes internal resilient stoppers 30 positioned in the void 36 toprevent the elliptical spring 26 from fully collapsing. The outsole 22may include forefoot section 32 and heel section 34. The heel section 34may be disposed on the undersurface of the elliptical spring 26, and theresilient stoppers 30 may be extensions of the heel section 34 that passinto the elliptical spring 26.

Although the present invention is illustrated in the context of anathletic shoe. It may, however, be incorporated into essentially anytype or style of footwear, including shoes, boots and sandals. It shouldbe noted that directional terms, such as “vertical,” “horizontal,”“top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and“outwardly,” are used to assist in describing the invention based on theorientation of the embodiments shown in the illustrations. Further, theterms “medial,” “lateral” and “longitudinal” are used in the mannercommonly used in connection with footwear. For example, when used inreferring to a side of the shoe, the term “medial” refers to the inwardside (i.e. the side facing the other shoe) and “lateral” refers to theoutward side. When used in referring to a direction, the term“longitudinal direction” refers to a direction generally extending alongthe length of the shoe between toe and heel, and the term “lateraldirection” refers to a direction generally extending across the width ofthe shoe between the medial and lateral sides of the shoe. The use ofdirectional terms should not be interpreted to limit the invention toany specific orientation(s).

For purposes of disclosure, the present invention is described in thecontext of an athletic shoe 10 having an upper assembly 12 formed usinga strobel construction. A sole assembly 14 in accordance with thepresent invention may, however, be combined with essentially any type orstyle of upper construction capable of being suitably joined with thesole component 20. The upper assembly 12 of the illustrated embodimentincludes an upper 15 formed from one or more layers of material that areshaped to form an enclosure of roughly the size and shape of a wearer'sfoot. The upper 15 of this embodiment may include quarters that form thesides and a vamp that closes the top. Foxing and other trim or extramaterial may be added to the upper 15 as desired for functional oraesthetic reasons. In this embodiment, the upper 15 includes a tongue 38and a closure system 40 to facilitate fitting and removal of the shoe 10on a wearer's foot. The tongue 38 and closure system 40 are generallyconventional and therefore will not be described in detail. The upper 15may include a heel counter. The heel counter may be a generallyconventional heel counter configured to provide control and stability tothe wearer's heel. For example, the upper 15 may include a rigid or semirigid insert that forms a sidewall in the heel region to seat thewearer's heel. In some embodiments, the heel counter may be eliminatedfrom the upper 15. In such embodiments, the heel cup 28 (described inmore detail below) of the sole component 20 may function as a heelcounter. In the illustrated embodiment, the bottom of the upper 15 isclosed using an insole board 16 (the upper surface of which isrepresented by a phantom line in FIG. 2). The peripheral edge of theinsole board 16 may be stitched or otherwise secured to the lastingallowance on the bottom edge of the upper 15. The insole board 16 may bemanufactured from any material suitable for forming an insole board. Forexample, the insole board 16 may be die cut from a nonwoven material,such as polyester fiber or leather.

As noted above, the sole assembly 14 of shoe 10 generally includes afootbed 18, a sole component 20 and an outsole 22. The footbed 18 ofthis embodiment is a generally conventional footbed that is manufacturedfrom a soft resilient material, such as EVA, PU or a gel material. Thefootbed 18 may be configured to be removably fitted into the upper 15atop the insole board 16. Alternatively, the footbed 18 may be securedto the top of the insole board 16, for example, by cement or adhesive.The size, shape and configuration of the footbed 18 may vary fromapplication to application. Although referred to as a footbed, footbed18 may alternatively be referred to as an insole or inner sole. Inaddition or as an alternative to the footbed 18, the sole assembly mayinclude a midsole (not shown) or other sole component disposed below thefootbed 18. In embodiments that incorporate a midsole, the midsole maybe disposed above or below the flex plate 18, or the flex plate 18 maybe embedded or partially embedded in a midsole (not shown).

The sole component 20 of the illustrated embodiment generally includes aflex plate 24, a heel spring 26 and a heel cup 28. In this embodiment,the flex plate 24, heel spring 26 and heel cup 28 are formed as a singleunitary component. However, they could be separately manufactured, ifdesired. In the illustrated embodiment, the flex plate 24 is alongitudinally extending plate-like component configured to generallycorrespond with the shape of the undersurface of a wearer's foot. Theflex plate 24 may extend from the heel region of the sole assembly 14 tothe forefoot region of the sole assembly. The peripheral edge of theflex plate 24 in the forefoot region is represented by broken line P inFIG. 4. As illustrated, the flex plate 24 may extend from the rear ofthe heel region forwardly to a point roughly beneath or just beyond themetatarsal heads of the wearer's foot. The length of the flex plate 24may, however, vary from application to application as desired. Forexample, in some applications, the flex plate 24 may be shortened sothat terminates short of the metatarsal heads. In the illustratedembodiment, the width of the flex plate 24 varies from region to region.For example, as shown, the flex plate 24 extends the full width of thesole assembly in the heel region and in the arch region, but extendsonly through a central section in the forefoot region. In thisembodiment, the width of the forefoot section tapers down from fullwidth in the arch region to its narrowest at the forward terminus. Thewidth of the flex plate 24 may vary from application to application toadjust the performance characteristics of the flex plate 24.

In the illustrated embodiment, the shape of the flex plate 24 variesfrom region to region. In this embodiment, the flex plate 24 may includea forefoot region 42, an arch region 44 and a heel region 46. As shown,the forefoot region 42 of the flex plate 24 may be generally planarfollowing a relatively slight curve configured to correspond with thegeneral shape of undersurface of a wearer's forefoot (See FIGS. 6-9). Inthe arch region 44, the flex plate 24 may have side walls 50 a-b thatextend upwardly to form a seat 52 that may receive and cradle thefootbed 18 and to provide the sole assembly 14 with enhancedlongitudinal support (See FIG. 8). In some applications, the side walls50 a-b may be of sufficient height to also receive and cradle thewearer's foot. Although not shown, the arch region 44 may be contouredto provide a raised arch support. For example, the flex plate 24 may beraised along a gradual curve on the medial side to provide support forthe arch of the wearer's foot. In applications where the arch region 44provides an arch support, the shape of the footbed 18 may be varied toaccommodate the arch support. The size, shape and configuration of theflex plate 24 can be varied to control the performance characteristicsof the flex plate 24. These variations may occur from region to regionto vary performance only a localized basis. For example, materials ofgreater hardness or materials of greater thickness may be used when itis desirable to increase the stiffness of the flex plate. As anotherexample, ridges, valleys, contours and other variations is shape orthickness may be incorporated into the flex plate 24 to allow overall orlocalized control.

In the illustrated embodiment, the heel cup 28 is an extension of theflex plate 24. As shown in FIGS. 4, 6 and 10, the heel region 46 of theflex plate 24 may be shaped to form the heel cup 28. Along the lateraland medial sides, the heel cup 28 may include the rearward portions ofthe side walls 50 a-b, which extend from the arch region 44 into theheel region 46. In the rear, the heel cup 28 may include a heelextension 54 that extends upwardly to follow along the rear of thewearer's foot. The heel extension 54 may extend along a gradual curveroughly matching the curve of the wearer's heel and be of sufficientheight and shape to form an undercut that resists upward separation ofthe wearer's heel from the sole assembly 14. As can be seen by referenceto vertical line V in FIG. 6, the undercut heel extension 54 extendsback over the rear of the heel to create a pocket that embraces the heelso that the heel cup 28 may move vertically with the heel. As shown, theheel extension 54 may include upper flanges 56 that extend forwardlyalong a gradual curve roughly matching the curve of the wearer's heel.In use, the heel extension 54 may operatively interact with the rear ofthe wearer's heel so that the heel cup 28 and full rearward extent ofthe flex plate 24 function as a lever that helps in applying a load(e.g. bending) the forefoot section 32 of the flex plate 24 during theforefoot compression phase of the gait cycle. The size, shape andconfiguration of the heel extension 54 may vary from application toapplication. For example, the height, width and/or thickness of the heelextension 54 may vary. Similarly, the size and/or shape of the upperflanges may vary. As noted above, the heel cup 28 may form the heelcounter for the shoe 10. In some applications, the heel cup 28 may varyto provide enhanced performance as a heel counter. For example, the heelcup 28 may include higher sidewalls 50 a-b. If desired, the sidewalls 50a-b and heel extension 54 may merge together into a single structurehaving a shape roughly similar to that of conventional heel counters.

As noted above, the sole component 20 also includes a heel spring 26.The heel spring 26 is generally disposed beneath the flex plate 24and/or heel cup 28 in the heel region of the sole component 20. Asshown, the heel spring 26 may extend higher than the forefoot section 32of the flex plate 24 to provide a raised “shelf” for the heel of thewearer's foot. The heel spring 26 may be an elliptical spring that isdisposed in the heel of the shoe 10 generally below the heel of thewearer's foot. In the illustrated embodiment, the heel spring 26includes an upper arched segment 60 and a lower arched segment 62. Thetwo arched segments 60, 62 are joined at opposite ends to provide aclosed cross sectional shape. Although referred to as an “elliptical”spring, it should be understood that the heel spring need not beprecisely elliptical in cross section. In fact, the heel spring may haveessentially any alternative shape, including shapes that are notelliptical. For example, the heel spring may be have a closed shape,such as circular, oblong, square, hexagonal, triangular, or “∞”-shaped,or an open shape, such as “C”-shaped, “S”-shaped, “Z”-shaped orsinusoidal. In the illustrated embodiment, the flex plate 24, heelspring 26 and heel cup 28 are integrally formed as a single unitarycomponent. In the embodiment, the upper arched segment 62 is anextension of the flex plate 24. For example, as shown, a forward portionof the upper arched segment 60 may be defined by and be essentiallycoextensive with the flex plate 24. The shape of the arched segments 60and 62 may vary from application to application for functional oraesthetic reasons. For example, the shapes of upper and lower archedsegments 60 and 62 may be selected to provide the desired resilientcompression. In the illustrated embodiment, the upper and lower archedsegments 60 and 62 cooperatively define an irregular ellipse. For boththe upper and lower arched segments 60, the radius of curvature may varyalong the segment. For example, in the illustrated embodiment, the upperarched segment 60 and the lower arched segment 62 increase in radiustoward the rear of the sole component 20. As a result, the ellipticalspring 26 is somewhat oblong with the rear end being larger than thefront end. The upper arched segment 60 and the lower arched segment 62may or may not be symmetrical with respect to one another. As perhapsbest shown in FIG. 9, the lower arched segment 62 may include a centralrail 64 that extends in the longitudinal direction. In use, the centralrail 64 may provide the lower arched segment 62 with increased strength,particularly in the longitudinal direction. The number, size, shape andconfiguration of the central rail 64 may vary from application toapplication. For example, the height and/or width of the central rail 64may vary to provide the desired performance characteristics or aestheticappearance. In the illustrated embodiment, the lower arched segment 62defines a plurality of apertures 70 (shown in broken lines in FIG. 4)that allow the stoppers 30 to be fitted into the void 36, as describedin more detail below. The number, size, shape and arrangement ofaperture 70 may be selected to correspond with the desired number, size,shape and arrangement of stoppers 30.

In the illustrated embodiment, the heel spring 26 is cantilevered beyondthe rearward end of the flex plate 24. The amount of cantilever may varyfrom application to application to vary the performance characteristicsof the sole assembly 14. Alternatively, the heel spring 26 may not becantilevered, but may instead co-terminate with the flex plate 24.

The elliptical spring 26 of this embodiment defines a central void 36and includes resilient stoppers 30 positioned in the void 36. In use,the resilient stoppers 30 function primarily to prevent the upper archedsegment 60 from bottoming out against the lower arched segment 62 underload. When the elliptical spring 26 has been sufficiently deformed by aload, the upper and lower arched segments 60 and 62 will “close onto thestoppers 30 and the stoppers 30 will provide enhanced resistance tofurther compression of the heel spring 26. The resiliency of thestoppers 30 may be selected to provide the desired resistance to furthercompression. The number, size, shape and configuration of the stoppersmay vary from application to application. In those embodiments thatinclude stoppers, the elliptical spring may include a plurality ofresilient stoppers 30 spaced apart from front to rear in a longitudinaldirection. In the illustrated embodiment, the elliptical spring 26includes two rows of stoppers 30. As shown, the elliptical spring 26 mayinclude a first row of stoppers 30 arranged near the lateral side of thesole component 20 and a second row of stoppers 30 arranged near themedial side of the sole. In the illustrated embodiment, each row ofstoppers 30 includes three stoppers 30. As perhaps best shown in FIG. 4,the stoppers 30 in each row are spaced-apart along an arcuate path thatroughly corresponds with peripheral shape of the sole component 20. Inthe illustrated embodiment, the various stoppers 30 are essentiallyidentical in size and shape, except that the center stopper in each rowhas a larger diameter than the other two stoppers in that row. Althoughthe illustrated embodiment includes six resilient stoppers 30, thenumber and arrangement of stoppers may vary from application toapplication. In some applications, the sole component 20 may not includeany stoppers.

In the embodiment of FIGS. 1-4, the stoppers 30 have approximately thesame height. The height of the stoppers may be selected for functionalreasons. For example, taller stoppers 30 will allow the spring tocollapse less before engagement with the stoppers 30. The relativeheight of the stoppers 30 may also vary for functional purposes. Forexample, in an alternative embodiment shown in FIG. 5, the height of thestoppers 30′ may increase toward the rear of the sole component 20′. Inuse, this may cause the heel spring 26′ to help to encourage forwardmotion. The reference numerals used in FIG. 5 correspond with those ofthe other Figs., except that they are followed by the prime symbol toindicate that FIG. 5 shows an alternative embodiment. The precisevariations in height may be varied to provide tailored control over theperformance characteristics of the heel spring.

In the illustrated embodiment, the stoppers 30 are manufactured from thesame material (e.g. the outsole material). In alternative embodiments,the stoppers 30 may be manufactured from different materials to allowthe performance characteristics of the sole assembly 14 to be tuned. Forexample, stoppers 30 positioned closer to the rear of the shoe may beharder than those positioned closer to the front. As another example,the medial row of stoppers may have a different hardness than thelateral row of stoppers to control pronation or supination.

In the illustrated embodiment, the stoppers 30 extend into the internalvoid 36 from lower arched segment 62. The stopper 30 may, however,extend from the upper arched segment 60 and/or the lower arched segment62.

In the illustrated embodiment, the sole component 20 is manufacturedfrom thermoplastic polyurethane elastomer (“TPU”), nylon or a polymerblend that includes nylon and/or TPU. The sole component 20 may,however, be manufactured from essentially any relatively hard polymer,such as nylon or an elastomer, or from other materials capable ofproviding the desired functional characteristics, such asfiber-reinforced polymers. Suitable elastomers may include thermoplasticelastomers or thermoset elastomers. Examples of suitable fiberreinforced polymers may include epoxy, polyethylene or polyesterthermosetting plastic reinforced with carbon, glass and/or aramidfibers.

As discussed above, the sole assembly 14 of the illustrated embodimentincludes an outsole 22 disposed below the sole component. The outsole 22is intended to provide a ground engaging surface and may haveessentially any configuration. In the illustrated embodiment, theoutsole 22 includes a forefoot section 32 and a heel section 34. Theoutsole 22 may, however, include essentially any number of parts. Forexample, the outsole 22 may be a single component that extends the fulllength of the sole. On the other hand, the outsole 22 may include evenmore than two separate parts. In the illustrated embodiment, theforefoot section 32 of the outsole 22 is secured to the undersurface ofthe upper 15 and the undersurface of the forefoot section 32 of the flexplate 24. For example, the forefoot section 32 of the outsole 22 may becemented or otherwise secured to the bottom of the upper 15 and the solecomponent 20 in the forefoot region of the shoe 10. The size, shape andconfiguration of the forefoot section 32 of the outsole 22 may vary, butin the illustrated embodiment the forefoot section 32 defines arectangular cutout 66 that exposes the flex plate 24 well into theforefoot region.

In the illustrated embodiment, the heel section 34 of the outsole 22 issecured to the undersurface of the heel spring 26. More specifically,the heel section 34 may be cemented or otherwise secured to theundersurface of the lower arched segment 62 of the heel spring 26. Inthis embodiment, the stoppers 30 are formed integrally with the heelsection 34 of the outsole 22. For example, the heel section 34 may beformed with protrusions that are configured to be fitted through theapertures 70 in the lower arched segment 62 into the void 36 to form thestoppers 30. Although not shown, each stopper 30 may be larger indiameter than the corresponding aperture 70 and may therefor include anintermediate shoulder that engages the upper surface of the lower archedsegment 62. To facilitate installation, each stopper 30 may have areduced diameter neck (not shown) that is configured to be seated in theaperture 70 when the stopper 30 is properly fitted into place. Theheight of the neck may be roughly equal to the thickness of the lowerarched segment 62. This provides a mechanical interlock between thestoppers 30 and the heel spring 26. In use, the intermediate shoulder(not shown) rests upon and distributes the forces created by downwardloads onto the lower arched segment 62, thereby preventing those loadsfrom being communicated through the apertures 70 to the underlyingoutsole 22.

The outsole 22 may have essentially any desired tread pattern. In theillustrated embodiment, the forefoot section 32 includes a plurality oflugs 76 or other tread details arranged inside the periphery of theforefoot section of the flex plate 24. These lugs 76 may help tocommunicate forces between the ground and the flex plate 24. In theillustrated embodiment, the heel section 34 of the outsole 22 includes aplurality of circular lugs 78 or other tread details positionedimmediately below the stoppers 30.

In the illustrated embodiment, the sole assembly 20 is configured sothat the heel section 34 of the outsole 22 projects roughly 2.0 mm belowthe projected ground line G, as shown by reference line B in FIG. 6.This offset may increase the “spring effect” of the heel spring.Further, when the sole assembly is subjected to standing weight, theheel spring 26 may compress slightly to partially offset thisdifference. The amount of offset may vary from application toapplication, as desired.

The above description is that of current embodiments of the invention.Various alterations and changes can be made without departing from thespirit and broader aspects of the invention as defined in the appendedclaims, which are to be interpreted in accordance with the principles ofpatent law including the doctrine of equivalents. This disclosure ispresented for illustrative purposes and should not be interpreted as anexhaustive description of all embodiments of the invention or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described invention may bereplaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as an alternative.Further, the disclosed embodiments include a plurality of features thatare described in concert and that might cooperatively provide acollection of benefits. The present invention is not limited to onlythose embodiments that include all of these features or that provide allof the stated benefits, except to the extent otherwise expressly setforth in the issued claims. Any reference to claim elements in thesingular, for example, using the articles “a,” “an,” “the” or “said,” isnot to be construed as limiting the element to the singular.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. An article of footwear having a heel region, an arch region and a forefoot region comprising: an upper; a sole assembly disposed toward a bottom of said upper, said sole assembly including: a flex plate extending from the heel region through the arch region into the forefoot region; and a heel spring disposed beneath said flex plate in the heel region, said heel spring and said flex plate being integrally formed as a single unitary component.
 2. The article of claim 1 wherein said heel spring has a closed shape defining an internal void.
 3. The article of claim 2 wherein said heel spring is generally elliptical in shape having an upper arched segment and a lower arched segment, said upper arched segment and said lower arched segment being joined at opposite ends.
 4. The article of claim 3 further including at least one resilient stopper disposed within said internal void.
 5. The article of claim 4 further including a plurality of stoppers disposed within said void, said stoppers varying in height.
 6. The article of claim 5 wherein said plurality of stopper increase in height toward a rear of the article of footwear.
 7. The article of claim 1 further including a heel cup, said heel cup disposed above said flex plate in said heel region.
 8. The article of claim 7 wherein said heel cup includes a sidewall and a heel extension extending upwardly from said flex plate; and wherein said heel cup, said heel spring and said flex plate being integrally formed as a single unitary sole component.
 9. The article of claim 8 wherein said heel extension include upper flanges that extend forwardly.
 10. The article of claim 9 further including an outsole disposed beneath said sole component.
 11. The article of claim 10 wherein said outsole includes a forefoot section and a separate heel section.
 12. The article of claim 11 wherein said heel section includes upwardly extending stoppers extending into said heel spring.
 13. The article of claim 10 wherein said heel spring is generally elliptical in shape having an upper arched segment and a lower arched segment, said upper arched segment and said lower arched segment being joined at opposite ends and defining an internal void; and wherein said heel section includes upwardly extending resilient stoppers that extend into said internal void to prevent said upper arched segment from collapsing onto said lower arched segment.
 14. The article of claim 13 wherein said lower arched segment defines a plurality of apertures, said stoppers extending through said apertures into said internal void.
 15. The article of claim 1 further including a footbed fitted into said upper and a heel cup extending form said flex plate; wherein said heel cup, said heel spring and said flex plate are integrally formed as a single unitary sole component, said sole component secured to an undersurface of said upper.
 16. The article of claim 15 wherein said heel spring is generally elliptical in shape having an upper arched segment and a lower arched segment, said upper arched segment and said lower arched segment being joined at opposite ends and defining an internal void; and further including at least one resilient stopper disposed in said internal void to prevent said upper arched segment from collapsing onto said lower arched segment.
 17. The article of claim 15 wherein said heel spring is generally elliptical in shape having an upper arched segment and a lower arched segment, said upper arched segment and said lower arched segment being joined at opposite ends and defining an internal void; and further including a plurality of resilient stoppers disposed in said internal void to prevent said upper arched segment from collapsing onto said lower arched segment.
 18. The article of claim 17 said plurality of stoppers increase in height toward a rear of said sole component.
 19. A sole assembly for an article of footwear: a flex plate having a heel portion, an arch portion and a forefoot portion; a heel spring disposed on an undersurface of said flex plate in said heel portion, said heel spring configured to bend under load; and a heel cup disposed on an upper surface of said flex plate in said heel portion, said heel cup having a medial sidewall, a lateral sidewall and a heel extension extending upwardly beyond said medial sidewall and said lateral sidewall.
 20. The assembly of claim 19 wherein said heel spring includes upper and lower segments cooperatively defining a void.
 21. The assembly of claim 20 further including a resilient stopper disposed in said void.
 22. The assembly of claim 19 wherein said heel spring is generally elliptical in shape, said heel spring including an upper arched segment and a lower arched segment, said upper arched segment and said lower arched segment joined at opposite ends and cooperatively defining a void.
 23. The assembly of claim 22 further including a resilient stopper in said void.
 24. The assembly of claim 22 further including an outsole disposed on said lower arched segment, said outsole having a protrusion extending through said lower arched segment into said void to form said resilient stopper.
 25. The assembly of claim 22 further including a plurality of resilient stoppers disposed in said void, said plurality of stopper increasing in height toward a rear of the sole assembly.
 26. The assembly of claim 25 wherein said heel spring includes a medial side and a lateral side, said resilient stoppers arranged in a first row extending along said medial side and a second row extending along said lateral side.
 27. The assembly of claim 21 wherein said extension of said heel cup follows a gradual curve and is undercut.
 28. The assembly of claim 27 wherein said heel cup includes upper flanges extending forwardly from said extension.
 29. The assembly of claim 27 wherein said heel spring is cantilevered beyond a rearward extent of said flex plate.
 30. The assembly of claim 29 wherein said lower arched segment includes a longitudinally extending rail.
 31. A sole component comprising: a flex plate having a heel portion, an arch portion and a forefoot portion; a heel spring extending downwardly from said flex plate in said heel portion, said heel spring including upper and lower segments configured to resiliently bend toward one another under load, said heel spring defining an internal void; a resilient stopper disposed with said internal void, said resilient stopper configured to prevent contact between said upper and lower segments under load; and a heel cup extending upwardly from said flex plate in said heel portion, said heel cup having a medial sidewall, a lateral sidewall and a heel extension extending upwardly beyond said medial sidewall and said lateral sidewall. 